Dual directional and brake light control for trailers

Abstract

A device for adapting combined brake and turn signal lights on a trailer to independent brake signal and turn signal lights on a towing vehicle has two circuits, one for each side, each circuit having a brake signal switch, such as a transistor, silicon-controlled rectifier or relay connected between the brake signal circuit of the vehicle and the filament of the combined brake and turn signal light on the corresponding side of the trailer. The brake signal switches are selectively actuated by impulses received from the corresponding turn signal flashers on the vehicle, to block the brake signal current to the corresponding signal light on the trailer. In one embodiment of the invention, voltage-sensitive switches (e.g., SCR) are connected to brake switch transistors, and the left-hand and right-hand turn signal circuits on the vehicle are connected through diodes to the corresponding signal lamps on the trailer, and also to their respective switches. When brakes are applied and turn signals simultaneously operated, the flashing turn signal triggers the voltage-sensitive switch on that side, causing the transistor to switch off, which prevents the brake circuit from lighting the combined lamp filament on that side while the filament is being flashed by the turn signal. The lamp on the other side remains lighted by the brake circuit. In another embodiment, relays or transistors are connected to the turn-signal circuits and brake signal circuits on each side of the towing vehicle in such a way that when one turn signal is operating the brake signal for that side is blocked by the turn signal voltage, and is passed when the turn signal voltage is off. Thus, the trailer turn signal lamp on the one side blinks at the same rate as the turn signal lamp on the vehicle, but 180° out of phase with the latter.

What I claim is: 
     
       1. A device for adapting combined brake- and turn-signal lights of a trailer to independent brake-signal and turn-signal lights on an associated towing vehicle, said towing vehicle having right- and left-turn flasher signal circuits and a brake-signal circuit, said trailer having right-hand and left-hand signal lights, each of which has a common filament for brake- and turn-signals, said device comprising: first switching means connected to both said right-turn flasher signal circuit and said brake-signal circuit on the vehicle, and also connected to said right-hand turn-and-brake signal light on the trailer;   second switching means connected to both said left-turn flasher signal circuit and to said brake-signal circuit on the vehicle, and also connected to said left-hand turn-and-brake signal light on the trailer;   each of said switching means being operable to transmit current from the corresponding turn flasher signal circuit or the brake signal circuit of the towing vehicle to the associated turn-and-brake signal light on the trailer when only one of said signal circuits on the vehicle is operating; and   each of said switching means being operable, responsive to the combined electrical current from both the brake signal circuit and the corresponding turn flasher signal circuit on the vehicle to switch current alternately on and off to the associated turn-and-brake signal light of the trailer, when both the brakes and turn signal flasher are operating;   the other turn-and-brake signal light on the trailer remaining continuously illuminated by current from the brake-signal circuit of the vehicle.   
     
     
       2. A device as in claim 1, wherein said first switching means includes means responsive to an electrical impulse from said right-turn flasher signal circuit in the vehicle to switch off transmission of electrical current from said brake-signal circuit of the vehicle to said right-hand signal light of the trailer, when both the brakes and right-turn signal of the vehicle are actuated, whereby the filament of the right-hand signal light is extinguished between flashes caused by electrical impulses from said right-turn signal circuit of the vehicle, while the filament of the left-hand signal light remains continuously illuminated by current from the brake-signal circuit of the vehicle; and said second switching means includes responsive to an electrical impulse from said left-turn flasher signal circuit on the vehicle to switch off transmission of electrical current from said brake-signl circuit of the vehicle to said left-hand signal light of the trailer when both the brakes and left-turn signal of the vehicle are actuated, whereby the filament of the left-hand signal light is extinguished between flashes caused by electrical impulses from said left-hand turn signal circuit of the vehicle, while the filament of the right-hand signal light remains continuously illuminated by current from the brake-signal circuit of the vehicle.   
     
     
       3. The device of claim 1, wherein each of said switching means includes a voltage-sensitive device that responds to an electrical impulse from the corresponding turn-signal circuit of the vehicle to switch off transmission of current from the brake signal circuit of the vehicle to the corresponding signal light of the trailer when both the brakes and turn-signal on the vehicle are actuated. 
     
     
       4. A device as in claim 1, wherein said first switching means includes a first diode connecting said right-turn signal circuit on said towing vehicle to the filament of said right-hand signal light on the trailer; and a first voltage-sensitive switch connected to said right-turn flasher signal circuit on the towing and operable, when said right-turn flasher signal circuit is actuated, to turn said first switching means off, so that the brake signal circuit of the towing vehicle is prevented from energizing the filament of said right-hand signal light on the trailer when the right-turn flasher signal is operating;   said second switching means including a second diode connecting said left-turn flasher signal circuit on said towing vehicle to the filament of said left-hand signal light on the trailer; and   a second voltage-sensitive switch connected to said left-turn flasher signal circuit on the towing vehicle and operable, when said left-turn flasher signal circuit is activated, to turn said second switching means off, so that the brake signal circuit of the towing vehicle is prevented from energizing the filament of said left-hand signal flasher on the trailer when the left-turn flasher signal is operating.   
     
     
       5. The device of claim 4, wherein said first and second switching means comprises first and second transistors, respectively, which are normally conducting, and which become non-conducting when their respective voltage-sensitive switch is actuated, thereby blocking current from said brake signal circuit of said towing vehicle to the common filament of the corresponding signal light on said trailer; said first diode being operable to transmit current from said right-turn signal circuit on said towing vehicle around said first transistor to said common filament of said right-turn signal light causes the latter to signal for a right turn; and said second diode being operable to transmit current from said left-turn signal circuit on said towing vehicle around said second transistor to said common filament of said left-turn signal to cause the latter to signal for a left turn. 
     
     
       6. The device of claim 5, wherein said first and second voltage-sensitive switches are silicon-controlled rectifiers (SRC), which are connected to the bases of their respective transistors, and which operate to switch off said respective transistors when actuated by voltage from the corresponding turn signal circuits. 
     
     
       7. A device as in claim 1, wherein said first switching means includes a first transistor having base, collector and emitter and a pair of diodes connected in parallel to the emitter thereof, one of said diodes being connected to the right-turn flasher circuit of the vehicle, and the other diode being connected to the brake signal circuit of the vehicle; means connecting the base of said first transistor to said right-turn flasher circuit ahead of said one diode;   other means connecting the base of said first transistor to said brake signal circuit ahead of said other diode;   the filament of said right-hand signal light on the trailer being connected to the collector of said first transistor;   said first transistor becoming forward-biased so that it is conductive from emitter to collector when the brake signal is "on" and the right-turn signal is "off", and said first transistor becoming non-conductive when the brake signal is "on" and the right-turn signal is "on";   said other means connecting the base of said first transistor to said brake signal circuit serving as a ground return for current from said right-turn flasher signal circuit when the latter is "on", thereby preventing said first transistor from being forward-biased when both the brake signal and right-turn signal are "on"; and   said second switching means including a second transistor and a pair of diodes connected in parallel to the emitter thereof, one of said last-named diodes being connected to the left-hand flasher circuit of the vehicle, and the other diode being connected to the brake signal circuit of the vehicle, said last-named diodes and said second transistor being connected and functioning in a manner similar to their counterparts of said first switching means.   
     
     
       8. A device as in claim 1, wherein said first switching means includes a normally-open first switch, the coil of which is connected serially between said right-turn flasher circuit and the brake signal circuit of the towing vehicle, said relay switch having a pair of contacts, one of which is connected to the right-hand signal light on the trailer; a first diode connecting said right-turn flasher circuit of the vehicle to the other of said pair of contacts on said first relay switch;   a second diode connecting said brake signal circuit of the vehicle to said other contact of said first relay switch;   said first relay switch being energized to close said normally-open contacts when either said right-turn signal circuit or said brake signal circuit is "on", and de-energized when both are "on", the filament of either the brake signal lamp or the right-turn signal lamp serving as a ground return for the coil of said first relay switch when one of the lamps is "off", whereby said relay switch coil id energized by the signal circuit that is "on";   said second switching means including a normally-open second relay switch, the coil of which is connected serially between said left-turn flasher signal circuit and the brake circuit of the towing vehicle, together with first and second diodes connecting the left-turn signal circuit and brake signal circuit, respectively of the vehicle to one contact of the second relay switch, the other contact of which is connected to the filament of the left-hand signal light on the trailer, said second relay switch and said last-named diodes functioning in the same manner as in said first switching means.